JP2000064805A - Different material welded rotor of steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase strength in a welding part and to make an inspection of a joining part easy, regarding a different material welded rotor jointed with rotors made of different kinds of materials by welding. SOLUTION: In a steam turbine rotor, a bearing part rotor 1 and a high temperature part rotor 2, the high temperature part rotor 2 and a low temperature part rotor 3 and the low temperature part 3 and a bearing part rotor 4 are jointed by welding parts A, B, C, respectively. In the welding parts B, C, each of space parts 5, 6 are formed. In the space parts 5, 6, inspection holes 7, 8 are provided, respectively. The rotor 1 is made of 2.(1/4) CrMoV, the rotor 2 is made of 12 Cr, and the rotors 3, 4 are made of NiCrMoV steel. The high temperature part rotor 2 is made of high heat resisting steel and others are made of low temperature alloys, material cost becomes inexpensive and inspections of the welding parts A, B, C in the inspection holes 7, 8 and the space parts 5, 6 become easy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dissimilar material welding rotor for a steam turbine, in which rotors made of different materials are joined by welding in a high temperature portion and a low temperature portion to increase joint strength, and
It also facilitates inspection of defects inside the rotor.

[0002]

2. Description of the Related Art In recent years, 12% chromium steel, which has excellent strength and toughness at high temperature, is used for the rotor of a steam turbine as the temperature of steam rises. Such a rotor uses the same 12% chrome steel for both the high temperature part exposed to high temperature steam and the low temperature part exposed to low temperature steam. It has become difficult to fabricate so as to satisfy the characteristics of 1. and the characteristics of the low temperature part. Further, the rotor part is made of 12% chrome steel, and the sleeve and coupling around the rotor are made of low alloy steel.

12% chrome steel is an expensive material, and the portion exposed to high temperature steam sufficiently satisfies heat resistance, creep characteristics, etc., but in the low temperature portion, such an expensive material is not required. Good and rather toughness is required, and low-temperature materials can be used. In order to deal with these problems, it has been attempted to join rotors made of different materials by welding as shown in FIG. 7 to form one rotor.

In FIG. 7, 31 is a turbine rotor of 12% chrome steel applied to a high temperature part, 32 is a turbine rotor made of a low alloy applied to a low temperature part, such as chromium, molybdenum, vanadium, nickel and molybdenum. It is made of alloys such as. Reference numeral 33 denotes a built-up portion, which is provided at the end portion 34 of the turbine rotor 31 and is made of 9Cr steel. Reference numeral 35 denotes a groove, which is formed between the built-up portion 33 to be joined and the turbine rotor 32 and is welded by the weld metal 36 to form one rotor.

[0005]

As described above, the conventional steam turbine rotor extends from the high temperature portion to the low temperature portion and is composed of a portion exposed to high temperature and high pressure steam and a portion exposed to low temperature and low pressure steam. There is. In the past, this steam turbine rotor was integrally molded using only 12% chrome steel,
Since 12% chrome steel is expensive, it has been proposed to join rotors made of different materials as shown in FIG. 7 to produce one rotor. However, in the conventional steam turbine rotor in which rotors made of different materials are joined, the welding strength may differ depending on the divided parts, and it is necessary to thoroughly inspect for defects after welding, but due to the structure, the inspection is sufficient. It is not considered that it can be carried out.

In view of the above, according to the present invention, in a steam turbine rotor constructed by joining dissimilar materials, in particular, the shape of the joining portion is devised, and the welding structure is made to increase the strength of the joining portion, and the joining portion is sufficiently inspected. It is an object of the present invention to provide a dissimilar material welding rotor for a steam turbine having a structure that can be carried out.

[0007]

The present invention provides the following means (1) to (3) in order to solve the above-mentioned problems.

(1) In a dissimilar material welding rotor of a steam turbine in which rotors made of different materials are divided into bearing parts, high temperature parts, and low temperature parts and joined by welding, the joint end faces of the rotors are circular at the center. It has a hollow part and has an annular surface that joins adjacent rotors in the peripheral part and is joined by welding to form a space part inside, and an inspection hole that communicates with the space part from the outer surface of the rotor is provided. A dissimilar material welding rotor for a steam turbine, which is characterized in that

(2) In a dissimilar material welding rotor of a steam turbine in which each rotor made of a different material is divided into a high temperature portion and a low temperature portion and welded to each other, the joint end surface of each rotor has a circular recess in the center. It has an annular surface that has an annular surface that is joined to the adjacent rotor at the peripheral portion and is joined by welding to form a space portion inside, and an inspection hole that communicates with the space portion from the outer surface of the rotor is provided. Dissimilar material welding rotor for steam turbine.

(3) In the above inventions (1) and (2), the inner periphery of the annular surfaces joined by welding is provided so as to protrude from the periphery of both side surfaces toward the center in the space. A dissimilar material welding rotor for a steam turbine, which is characterized in that

In (1) of the present invention, the rotor is divided into a bearing portion at both ends, a high temperature portion, and a low temperature portion and welded, and in (2) of the present invention, the low temperature portion and the high temperature portion. , Both ends are composed of a low temperature part and an intermediate high temperature part, and are welded. Such a dissimilar material welding rotor of a steam turbine has a space portion inside the welded portion, and the space portion is provided with an inspection hole communicating from the outer surface of the rotor to the inside. Etc. can be inserted into the space to inspect the periphery of the welded joint.

In (3) of the present invention, since the periphery of the welded joint in the space is projected from both side surfaces toward the center by a predetermined length, the tensile stress at the joint is from the outer peripheral side. Also, the inner peripheral side is dispersed and weakened by the projecting portion, and damage at the inner end of the joint surface due to thermal stress can be prevented.
Further, when the radius of the curved surface forming the protruding portion is R and the length of the protruding portion after joining is L, the stress reducing effect becomes large when L / R is in the range of 2 <L / R <3. .

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a sectional view of a dissimilar material welding rotor of a steam turbine according to a first embodiment of the present invention. In the figure, 1 is a bearing rotor, 2 is a high temperature rotor, 3 is a low temperature rotor, and 4 is a low temperature bearing rotor. The bearing portion rotor 1 and the high temperature portion rotor 2 are welded portions A, and the high temperature portion rotor 2 and the low temperature portion rotor 3 are welded portions B.
The low temperature portion rotor 3 and the bearing portion rotor 4 are welded and joined together at the welded portion C to form a single steam turbine rotor.

The bearing portion rotor 1 is a low temperature portion, and 2 * (1
/ 4) CrMoV (chromium molybdenum vanadium) steel is used. Since the high temperature rotor 2 is exposed to high temperature steam and is the most thermally severe part, it is made of 12Cr steel having high heat resistance and excellent strength. The low temperature part rotor 3 is also a part exposed to steam, but since the low temperature part rotor 3 has relatively low pressure and low temperature, 3.5NiCrMo.
V (nickel / chromium / molybdenum / vanadium) steel is used, and the bearing rotor 4 is also made of the same material.

The welded portions B and C are the portions related to the rotors 2 and 3 exposed to high temperature and low temperature steam, respectively, and are the important portions to which the rotor blades of the turbine are attached. As will be described later, the space portions 5 and 6 are provided so that the periphery of the welded portions B and C can be inspected. The welded portion A is a low temperature bearing portion, and the hollow portion 10
Since such a structure is not adopted because a fiberscope or the like can be inserted and can be inspected, it is needless to say that such a similar structure may be provided if necessary.

FIG. 2 is a sectional view showing the welded structure of each of the welded portions A, B and C in FIG.
(B) shows a welded portion B, and (c) shows a welded portion C, respectively.
In (a), the high temperature portion rotor 2 is made of a high heat resistant material of 12Cr steel, and the built-up portion 12 of 9Cr steel is used to prevent softening. Bearing part rotor 1 is 2 · (1/4) C
It is made of rMoV steel, and a groove 13 is formed between the bearing rotor 1 and the overlay 12, and welding is performed with the weld metal 11.

In FIG. 2B, the high temperature part rotor 2 is 12C.
The protrusion 22 is made of r steel and is formed on the space 5 side, and the built-up portion 14 made of 9Cr steel is provided as in (a). The low temperature portion rotor 3 is made of 3.5NiCrMoV steel and also has the protrusions 23 formed thereon.
A groove 15 is machined between and, and welded with a weld metal 16. In addition, the corner of the low temperature rotor 3 is 2 · (1 /
4) Welded with CrMo to prevent reheat cracking.

In FIG. 2 (c), the low temperature section rotor 3 has 3.5
The protrusion 24 is formed of NiCrMoV steel on the side of the space 6, the bearing rotor 4 is made of the same material, and the protrusion 25 is also formed. Both protrusions 24, 25
The groove 18 is machined at the joint of and welded with the weld metal 19, and both corners are treated as a countermeasure against reheat cracking.
/ 4) Welded with CrMo steels 20 and 21.

FIG. 3 is a partially enlarged sectional view of FIG.
(A) is an enlarged cross-sectional view of the X portion of FIG. 1, and (b) is an enlarged cross-sectional view of the B portion in (a). In the drawing, circular recesses 26 and 27 are formed in the welded portions B and C, respectively, and space portions 5 and 6 are formed by the pair of left and right recesses 26 and 27 in the joint portion. Inspection holes 7 and 8 communicating with the rotor surface are provided in the space portions 5 and 6, respectively.

In FIG. 3B, the high temperature rotor 2 made of 12Cr steel has a smaller coefficient of thermal expansion than the high temperature rotor 2 and the low temperature rotor 3, and the low temperature rotor 3 shrinks faster. become. Therefore, the inspection hole 7 has a small coefficient of thermal expansion and is provided on the side of the high temperature part rotor 2 which is less affected by heat and is communicated with the space part 5. The inspection hole may be provided at a position adjacent to the welded portion, and at least one inspection hole may be provided on the outer circumference of the rotor, if necessary.

Further, the inspection hole 7 is always provided with a plug 9 and is hermetically sealed. At the time of inspection, the plug 9 is removed, a fiberscope or the like is inserted into the space 5 through the inspection hole 7, and the periphery of the welded portion B is inspected. can do. The plug 9 can be easily fixed and removed by screwing it into the entrance of the inspection hole 7 with a screw or the like. Also in the welded portion C, the low temperature portion rotor 3 and the bearing portion rotor 4 are made of the same material, but the position of the inspection hole 8 is provided on the high temperature side according to the welded portion B.

FIG. 4 is a stress distribution diagram in the welded portion B. In the figure, protrusions 22 and 23 are formed on the space portion 5 side of the joint portion with the high temperature portion rotor 2 and the low temperature portion rotor 3, respectively. The joint portion B receives a tensile stress F due to thermal expansion, but the stress is linearly applied to the left and right in the vicinity of the welded portion B ₁ , but the tensile stress is dispersed by the protrusions 22 and 23 in the vicinity of the welded portion B _{2. It} is smaller than ₁ part and can prevent cracking due to tensile stress at the B _O point. Further, if the radius of the curved surface forming the protrusions 22 and 23 in the figure is R and the length of both protrusions 22 and 23 is L, the stress reduction effect is most effective in the range of 2 <L / R <3. growing.

As described above, in the weld portion of the dissimilar material welding rotor according to the first embodiment of the present invention, B, C which are particularly exposed to high temperature steam.
In the portion, the space portions 5 and 6 are provided, and the projection portions 22 and 23, 24 and 25 are formed on the space portions 5 and 6 side to reduce the tensile stress due to thermal expansion, and further the inspection holes 7 and 8 are formed. Since the space is provided so as to communicate with the space portions 5 and 6, the strength of the dissimilar material welding rotor in which the rotors made of different materials are joined is increased, and the joint portion can be easily inspected. FIG. 5 is a sectional view of a dissimilar material welding rotor according to the second embodiment of the present invention. The second embodiment is different from the first embodiment shown in FIG. 1 in the low temperature part rotor indicated by reference numerals 41 and 42, and the high temperature part rotor 2 and its internal structure are the same as those in FIG. is there.

In the figure, the low-temperature part rotor 41 and the high-temperature part rotor 2 are welded to each other at a welded portion A, and the high-temperature part rotor 2 and the low-temperature portion rotor 42 are welded to each other at a welded part B to form one steam turbine rotor. is doing. Low temperature section rotors 41 and 42
Is the low temperature part, and CrMoV (chrome molybdenum
Banadium steel is used. The welded portion B is a portion related to the high temperature portion rotor 2 and the low temperature portion rotor 42 which are exposed to the high temperature and low temperature steam, and is an important portion to which the moving blades of the turbine are attached. Therefore, the same as in the first embodiment. It has a structure.

The welded portions A and B are the same as the welded structure shown in FIGS. 2 (a) and 2 (b) of the first embodiment. Although not shown, the high temperature rotor 2 is shown in FIG.
The other side of the bearing rotor 1 instead of the low temperature rotor 4
In 1 and (b), the low temperature portion rotor 3 is replaced by the low temperature portion rotor 42, and the welded portion C shown in (C) does not exist. Since other configurations are the same, description thereof will be omitted.

FIG. 6 is a partially enlarged sectional view of FIG. 5, (a) is an enlarged view of the welded portion B of FIG. 5, and (b) is a detail of the joint portion, which is basically the first embodiment. FIG. 3 in one form
It has the same configuration as that of the above, but does not include the welded portion C of FIG. 3. In the figure, recesses 26 and 27 are formed in the welded portion B, and a space 5 is formed by the pair of left and right recesses 26 and 27 in the joint. An inspection hole 7 communicating with the surface of the rotor 2 is provided in the space 5.

Further, the inspection hole 7 is the same as in the first embodiment,
It is installed on the rotor side of the high temperature part where heat influence is small.
As shown in the figure, the plug 9 is always provided and sealed,
At the time of inspection, this can be removed and a fiberscope or the like can be inserted into the space 5 through the inspection hole 7 to inspect the periphery of the welded portion B. The plug 9 can be easily fixed and removed by screwing it into the entrance of the inspection hole 9 with a screw or the like. In addition, as in the first embodiment, the inspection hole 7 may be provided at a position adjacent to the welded portion, and may be provided at least at one position on the outer circumference of the rotor, or at a plurality of positions as necessary.

According to the dissimilar material welding rotor of the second embodiment as described above, there are two rotor joining portions A and B as compared with the rotor of the first embodiment, and the welding portion C shown in FIG. 1 exists. Without doing so, the workability of the welding rotor becomes better than that of the first embodiment, and a fiberscope or the like can be inserted from the inspection hole 7 of the welded portion B, and the same effect as that of the first embodiment can be obtained. It is a thing.

[0029]

The dissimilar material welding rotor for a steam turbine according to (1) of the present invention is divided into a bearing portion, a high temperature portion, and a low temperature portion, and the rotors of different materials are joined by welding. Section and a low temperature section, each rotor is joined by welding, and the joining end surface of each rotor has a circular recess in the center and an annular surface that joins adjacent rotors in the peripheral section. It is characterized in that it is joined by welding to form a space inside, and an inspection hole communicating from the outer surface of the rotor to the space is provided. With this configuration,
Insert the fiberscope etc. into the space through the inspection hole,
Since the periphery of the welded joint can be inspected, welding defects of the dissimilar material welding rotor are prevented.

(3) of the present invention includes the above (1) or (2).
The invention is characterized in that the inner periphery of the annular surfaces joined by welding is provided so as to project from the periphery of both side surfaces toward the center in the space portion. With such a configuration, the tensile stress due to the thermal expansion at the welded joint surface is spread and dispersed in the protruding portion and weakened, damage at the joint end surface due to thermal stress is prevented, and the reliability of the dissimilar material welding rotor is improved.

[Brief description of drawings]

FIG. 1 is an overall cross-sectional view of a dissimilar material welding rotor of a steam turbine according to a first embodiment of the present invention.

FIG. 2 shows a welded portion in FIG. 1, in which (a) is a sectional view of a welded portion of a bearing portion and a high temperature portion, (b) is a high temperature portion and a low temperature portion, and (c) is a welded portion of a low temperature portion and a bearing portion.

3 is an enlarged view in FIG. 1, (a) is an enlarged cross-sectional view of an X part in FIG. 1, and (b) is an enlarged detailed view of a B part in (a).

FIG. 4 is a tensile stress distribution diagram of a welded portion B in FIG.

FIG. 5 is an overall sectional view of a dissimilar material welding rotor of a steam turbine according to a second embodiment of the present invention.

6 is an enlarged view of FIG. 5, (a) is an enlarged view of a B portion, and (b) is a detailed view of (a).

FIG. 7 is a partial cross-sectional view of a conventional steam turbine rotor in which dissimilar materials are joined.

[Explanation of symbols]

1,4 Bearing rotor 2 High temperature part rotor 3,41,42 Low temperature part rotor 5, 6 Space section 7,8 inspection hole 9 plugs 10 Hollow part 11, 16, 19 Weld metal 12,14 Overlay part 13,15,18 groove 22,23,24,25 Projection 26, 27 depression

Claims (3)

[Claims] 1. A dissimilar material welding rotor for a steam turbine, wherein a rotor, which is divided into a bearing portion, a high temperature portion, and a low temperature portion, is joined by welding. And an inspection surface that connects the adjacent rotors to each other at the periphery and has an annular surface that is welded to form a space inside and that communicates from the rotor outer surface to the space Dissimilar material welding rotor for steam turbine. 2. In a dissimilar material welding rotor of a steam turbine, which is divided into a high temperature part and a low temperature part and is joined by welding, the rotors made of different materials are joined to each other. In addition, it is characterized in that it has an annular surface that is joined to an adjacent rotor in the peripheral portion and is joined by welding to form a space portion inside, and that an inspection hole that communicates from the outer surface of the rotor to the space portion is provided. Dissimilar welding rotor for steam turbine. 3. The steam according to claim 1, wherein the inner periphery of the annular surfaces joined by welding is provided so as to project from the periphery of both side surfaces toward the center in the space portion. Dissimilar material welding rotor for turbine.